The present invention relates generally to the field of writing instruments and in particular to a new and useful mechanism for expanding the length of a writing instrument barrel while extending a writing tip from a retracted position in the barrel to a writing position.
Compact devices of all types are sometimes preferred over full-size versions because they occupy less space. However, some compact devices are not as useful as full-sized versions of the same product for a variety of reasons.
In the case of writing instruments, a small or reduced size pen can be difficult to hold and use for many people, including the elderly, children, the infirm, and people with large fingers. At the same time, a pen or pencil which occupies less space is more easily carried in a pocket or purse.
Sometimes, pens and pencils are sized to fit with other products they are used with, such as a miniature pen provided with a date planner or a golf pencil stored on the steering wheel of a golf cart. These smaller pens and pencils are non-refillable and must be discarded when the ink or lead is used up. While these writing instruments are a compact, convenient size for storing, they are not as comfortably for writing with and suffer the problem that they can be difficult for some persons to use.
Attempts to provide pens having extendable bodies, include a miniaturized ball point pen which is expandable to a more comfortable length for use as disclosed in U.S. Pat. No. 3,174,461. The pen point is always exposed and does not retract within the body of the pen. The body expands by simply sliding two concentric overlapping sections apart. The overlapping sections are frictionally fit to each other. A lower section secures the ball point and ink supply inside the body. The upper section slides inside the lower section and has a tapered end which catches the top of the ink supply to prevent the upper section from being completely separated from the lower section. A cap fits over the upper section and its lower edge stops against the upper edge of the lower section.
U.S. Pat. No. 3,709,620 teaches a ball point pen having a body which is expandable for use as a pointer. The pen body is formed by a series of telescoping tubes which support and contain the ball point and ink supply. The ball point may be extended or retracted from the pen body by a spring-loaded operation button at the top end of the body. The button has a horizontal channel with a spring-loaded slider having a tab which is forced into an opening in the side of the upper tube when the button is depressed to hold the button and keep the pen tip extended. Pressing the top end of a clip mounted outside the upper tube over the tab pushes the tab and slider back within the button, releasing the button from the depressed position. The button spring may then force the button back upward, retracting the pen tip.
While the pen tip may be retracted in this pen, it requires a relatively complex arrangement of springs and sliders and it requires the presence of a clip. The extension/retraction mechanism for the pen tip is not integrated with the expansion for the device either. The pen tip cannot be extended outside the pen point when the tubes are expanded for use as a pointer.
A folding ball point pen is disclosed by U.S. Pat. No. 5,061,104. The pen is hinged near the center of the pen and a recess is provided in the upper section, so that the lower section containing the pen point and ink reservoir may be folded flush into the side of the upper section. The pen point is not retractable.
These prior pens suffer from the problem that either the pen tip is always exposed, which either requires the use of a pen cap, or there is the risk of accidental marks. The pen is not replaceable; once the ink is used up, the device must simply be thrown away and replaced in its entirety.